Nasal septal abscess is an uncommon condition. This paper describes a case of nontraumatic, nasal septal abscess in an immune-competent child with no evidence of sinusitis or other localized infections. A 7-month-old infant with a 2-day history of nasal obstruction, fever, and a swollen, erythematous nose was admitted to our hospital. Physical examination revealed that the swelling of the nasal mucosa emanated from the septum. Computed tomography of the sinuses revealed a nasal septal abscess encompassing the entire nasal cavity. After drainage, the patient showed satisfactory recovery. Early diagnosis and prompt treatment, including incision and drainage and appropriate antibiotic coverage, are required to avoid serious complications.